The present invention relates generally to underground drilling machines. More particularly, the present invention relates to systems or methods for anchoring underground drilling machines for use in horizontal directional drilling.
Utility lines for water, electricity, gas, telephone and cable television are often run underground for reasons of safety and aesthetics. Sometimes, the underground utilities can be buried in a trench that is then back filled. However, trenching can be time consuming and can cause substantial damage to existing structures or roadways. Consequently, alternative techniques such as horizontal directional drilling (HDD) are becoming increasingly more popular.
A typical horizontal directional drilling machine includes a frame on which is mounted a drive mechanism that can be slidably moved along the longitudinal axis of the frame. The drive mechanism is adapted to rotate a drill string about its longitudinal axis. Sliding movement of the drive mechanism along the frame, in concert with the rotation of the drill string, causes the drill string to be longitudinally advanced into or withdrawn from the ground.
In a typical horizontal directional drilling sequence, the horizontal directional drilling machine drills a hole into the ground at an oblique angle with respect to the ground surface. During drilling, drilling fluid can be pumped through the drill string, over a drill head (e.g., a cutting or boring tool) at the end of the drill string, and back up through the hole to remove cuttings and dirt. After the drill head reaches a desired depth, the drill head is then directed along a substantially horizontal path to create a horizontal hole. After the desired length of hole has been drilled, the drill head is then directed upwards to break through the ground surface. A reamer is then attached to the drill string which is pulled back through the hole, thus reaming out the hole to a larger diameter. It is common to attach a utility line or other conduit to the drill string so that it is dragged through the hole along with the reamer.
During drilling and pull-back operations, substantial forces are applied to the drill string. Thus, during directional drilling operations, it is important for a directional drilling machine to be xe2x80x9canchoredxe2x80x9d or xe2x80x9cstaked-downxe2x80x9d to prevent the directional drilling machine from moving during drilling or pull-back sequences.
One aspect of the present invention relates to a horizontal directional drilling machine for generating a bore with a drill string. The machine includes a frame defining a thrust axis. A rotational drive head for rotating the drill string is mounted on the frame. A thrust mechanism is provided for moving the rotational drive head in a first direction along the thrust axis to push the drill string into the ground, and a second direction along the thrust axis to pull the drill string from the ground. The horizontal directional drilling machine also includes an anchoring arrangement connected to the frame. In one embodiment, the anchoring arrangement includes a stake-down unit that is pivotally movable about a pivot axis that is generally transversely oriented relative to the thrust axis. The stake-down unit includes a power auger, and a stake-down actuator for moving the power auger toward and away from the ground. The anchoring arrangement also includes a tilt actuator for pivoting the stake-down unit about the pivot axis. In another embodiment, the anchoring arrangement can include a stake-down unit as described above that is laterally adjustable relative to the thrust axis.
Another aspect of the present invention relates to an anchoring assembly for a directional drilling machine. The anchoring assembly includes a stake-down mount adapted to be pivotally connected to the directional drilling machine. The anchoring assembly also includes a first and second stake-down units connected to the stake-down mount. Each of the stake-down units includes a power auger and a stake-down actuator. The first stake-down unit is connected to the stake-down mount by a lateral extension member that is mounted to slide relative to the stake-down mount.
A further aspect of the present invention relates to a method for anchoring a horizontal directional drilling machine including a frame having a thrust axis. The method includes aligning the thrust axis at an oblique angle relative to the ground; pivoting a power auger of the directional drilling machine about a tilt axis generally transversely aligned relative to the thrust axis; and driving the pivoted power auger into the ground.
A variety of advantages of the invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practicing the invention. It is to be understood that both the foregoing general description and the following detailed description are explanatory only and are not restrictive of the invention as claimed.
The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate several aspects of the invention and together with the description, serve to explain the principles of the invention. A brief description of the drawings is as follows:
FIG. 1 shows a horizontal directional drilling machine adapted for use with an anchoring system constructed in accordance with the principles of the present invention;
FIG. 2 is a perspective view of an anchoring system constructed in accordance with the principles of the present invention, the anchoring system is shown in a laterally retracted orientation;
FIG. 3 is a perspective view of the anchoring system of FIG. 2 with the anchoring system in a laterally extended orientation;
FIG. 4 is a top view of the anchoring system of FIGS. 2 and 3;
FIG. 5 is a schematic cross-sectional view showing a lateral extension mechanism for extending one of the stake-down units of FIGS. 2 and 3;
FIG. 6 is a side view of the anchoring system of FIGS. 2 and 3 with the power auger of one of the stake-down units in a raised orientation;
FIG. 7 is a side view showing the anchoring system of FIGS. 2 and 3 in a backwardly tilted orientation; and
FIG. 8 shows the anchoring system of FIGS. 2 and 3 in a forwardly tilted orientation.